bioTCIs: Middle-to-Macro Biomolecular Targeted Covalent Inhibitors Possessing Both Semi-Permanent Drug Action and Stringent Target Specificity as Potential Antibody Replacements.

Monoclonal antibody therapies targeting immuno-modulatory targets such as checkpoint proteins, chemokines, and cytokines have made significant impact in several areas, including cancer, inflammatory disease, and infection. However, antibodies are complex biologics with well-known limitations, including high cost for development and production, immunogenicity, a limited shelf-life because of aggregation, denaturation, and fragmentation of the large protein. Drug modalities such as peptides and nucleic acid aptamers showing high-affinity and highly selective interaction with the target protein have been proposed alternatives to therapeutic antibodies.

Solvatochromic peptidic binder obtained via extended phage display acts as a fluororeporter for fragment-based drug discovery (FBDD).

We have previously established a selection system to obtain a solvatochromic protein binder from a peptidic fluoroprobe library via the extended T7 phage display. Here, we use the peptidic binder as a fluororeporter in this proof-of-concept study of fragment-based screening approach to drug discovery. The binder is released from the target protein on mixing with an appropriate lead compound, thereby altering its fluorescence color/intensity under 365 nm ultraviolet wavelength irradiation.

Direct screening of a target-specific covalent binder: stringent regulation of warhead reactivity in a matchmaking environment.

A peptide-type covalent binder for a target protein was obtained by direct and stringent screening of a warhead-modified peptide library on the robust T7 phage. The aryl fluorosulfate (fosylate) warhead was activated only in a matchmaking microenvironment created between the target protein and an appropriate peptide during the reactivity/affinity-based co-selection process of extended phage display.